Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

526
FXUS63 KLOT 232352
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
652 PM CDT Tue Jun 23 2026

.KEY MESSAGES...

- Chance of thunderstorms returns Wednesday, some possibly
  becoming strong in the afternoon. Periodic, but low, chances
  for storms then continue through the end of the week into the
  weekend.

- Turning hotter and more humid into early next week.

&&

.DISCUSSION...
Issued at 211 PM CDT Tue Jun 23 2026

Main forecast concern is thunderstorm chances Wednesday into
Wednesday night as an upper level trough and associated surface
low moves across the Great Lakes region. Showers and scattered
thunderstorms across MN are expected to continue moving
southeast into south/central WI tonight. There is still quite a
bit of uncertainty regarding how far south this activity may
move, possibly reaching far northern IL in the predawn hours
with a bit better chance for at least showers across northern IL
Wednesday morning. As a cold front moves across the area
Wednesday afternoon into Wednesday evening, scattered
thunderstorms will be possible and while instability may be
limited, the wind field is sufficient for any organized storms
to possibly become strong to severe and trends will need to be
monitored.

Models are slowly trending further south with precip chances for
Thursday and Friday, though still chances across the southern
cwa, especially later Friday into Friday night. There will still
be a chance for showers and thunderstorms over the weekend as
the upper ridge builds across the area. The best timing
continues to fall in the Saturday afternoon to Sunday afternoon
time frame, with perhaps the best chance now looking to be in
the late Saturday night/early Sunday morning time period. Quite
a bit of uncertainty, but it will need to be monitored for
possible strong storms/heavy rain.

The ridge then builds into the region Sunday into Monday with
warmer and more humid air spreading across the region with highs
on Sunday likely in the upper 80s and lower 90s on Monday. While
much of next week currently appears to be very warm/hot and
humid, there are concerns for how close the local area will be
to the edge of the ridge and for how close thunderstorm
activity may evolve, especially by Monday night into Tuesday,
which could have large impacts on temperatures. cms

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 651 PM CDT Tue Jun 23 2026

Aviation forecast concerns for the 00Z TAFs:

- Easterly lake breeze winds become southeast this evening, with
  southwest winds gusting 15-20 kt at times on Wednesday.

- Periods of SHRA likely by mid-late morning, with scattered
  TSRA possible Wednesday afternoon/early evening.

Surface high pressure was over the western Great Lakes region
early this evening, supporting modest lake breeze winds off of
Lake Michigan. These east-northeast winds will diminish and
become light southeast through the evening, before eventually
turning light south-southwest predawn Wednesday as the surface
high pressure ridge drifts away to the east.

An area of low pressure currently over the upper Midwest (ND/MN
border region) will track east across WI on Wednesday in
association with a mid-level disturbance, and will trail a weak
cold front across the terminals later Wednesday night. Scattered
showers are expected to spread across southern WI and the IL/WI
border region around/after daybreak Wednesday, in a region of
modest but persistent warm/moist advection. These showers will
likely eventually spread southeast across the terminals during
the early to mid-morning hours and persist into the afternoon.
Thunder potential initially appears low (less than 30%), but
does look to increase during the afternoon during peak diurnal
warming. Some detail/coverage/timing differences remain in high-
res model guidance, though convectiion-allowing ensembles focus
highest thunder chances (~40%) after ~20Z at KRFD and after ~22Z
in the Chicago metro area. Have indicated prevailing VCSH and
PROB30 TS mentions in the TAFs for now, though if confidence
increases could see the need for TEMPO mentions with later
forecasts.

Otherwise, VFR conditions are expected, with winds becoming
southwest with gusts 15-20 kt during the day Wednesday.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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